Impact damage detection in composite structures using active acousto-ultrasonic sensors

Impacts with ground support equipment are the major cause of in-service damage to composite structures. This paper addresses the problem of impact damage detection in composite structures using acousto-ultrasonic sensors. The impacts are taken from a simple experiment in which piezoceramic, devices are used in active mode to acquire the ultrasonic data. One piezoceramic activates the structure with the high-frequency excitation. The second piezoceramic is used for data acquisition. The ultrasonic waves passing through the structure are analysed to reveal damage. Autoregressive spectrum and time-frequency analysis employing the wavelet transform is used for damage feature selection. The study includes different levels of impact energy and different types of damage such as indentation, matrix cracking delamination, fibre fracture and perforation. The analysis of the impact data reveals the features which can be correlated with the structural damage.